Colored Rings Around the Sun Captured in Finland; How Does Pollen Corona Happen?

The sun constantly demonstrates behaviors seen here on Earth, usually due to its magnetic fields and the movement of its charged particles. For instance, giant solar eruptions lead to flares and coronal mass ejection. Experts can also observe the formation and disappearance of dark sunspot millions of kilometers away.

In some cases, however, the strange behavior of the sun is due to Earth-based origin. Just recently, shining rainbow rings resembling kaleidoscope circles were spotted around the sun.

Pollen-Triggered Rainbow Rings Around the Sun

The sun was spotted in Finland with strange concentric rainbow-like haloes surrounding it on May 30. It was captured by Mikko Peussa as he observed this phenomenon near his home in Turku

The bizarre phenomenon known as "pollen coronas" is due to pine pollen floating in the air and causing the formation of multicolored rings. Individual pollen particles cause the star-like glow in and around the colored rings.

The eye-catching sight is created by the refraction of light, where it separates into its wavelengths upon hitting the surface of the pollen grains. As some of the wavelengths of light interfere with or hit one another, only selected colors reach the eye of the observer. This interference is also known as a diffraction pattern.

Pollen coronas are smaller compared to other solar halos. They also have their distinct shape due to the shape of pollen grains. Contrary to popular belief, pollen grains are usually not spherical. Instead, they have elongated shapes containing air sacs to assist the process of wind dispersal. This irregular shape of the pollen particles gives the oval shape of the halos. The coronas become more elongated and oval-shaped as the sun lowers in the sky.

This event does not often happen, as it only occurs when there are high concentrations of pollens in the air and when the sun or the full moon is partially blocked. At this moment, pollen grains are present in the air in high concentrations due to springtime bloom—the coronas as best set by pollen particles from trees such as birch, spruce, and pine.

Experts also believe that the concentration of pollen grains in the air and the length of pollen seasons could increase due to rising carbon dioxide levels in the atmosphere caused by human activity. This means that pollen coronas could be seen more frequently in the future.

Other Phenomena Involving the Sun

Other atmospheric events happen when the light from the sun gets refracted by objects that float in the air. There are moments when the sun seems surrounded by two bright companions. This is called sun dogs, a solar event where concentrated pillars of light appear on the sun's left or right side. Also known as mock suns, this phenomenon happens due to the refraction of light by ice crystals suspended in the Earth's atmosphere.

Another product of the refraction of sunlight is a fog bow, sometimes known as a white rainbow or cloud bow. This arc forms over the horizon like a regular rainbow is created. However, as the classical rainbow is formed from the interaction of sunlight with raindrops, the fogbow results when the light interacts with water droplets suspended in a fog or cloud.